A. Field of Invention
The present invention relates to a novel manual wheelchair (MWC) structure that enables a wheelchair user to more readily propel and brake the wheelchair in forward and rearward directions in a safe manner and with biomechanical efficiency that reduces the likelihood of injury to the user. More particularly, the application pertains to a novel manual wheel chair having an improved propulsion mechanism that can be used to move the same.
B. Description of the Prior Art
The present invention relates to a novel component for wheelchairs. The invention enables a wheelchair user to more readily propel and brake the wheelchair in forward and rearward directions in a safe manner and with biomechanical efficiency that reduces the likelihood of injury to the manual wheelchair (MWC) user. There are currently approximately two million MWC users in the United States. The vast majority of these users operate their wheelchairs according to the standard propulsion method utilizing handrims secured to the perimeter of each main wheel. By grasping the handrims and forcing their rotation, the main wheels rotate, propelling the wheelchair. Differential application of force is applied to change the lateral direction of the wheelchair. To propel a MWC according to this standard method requires that the user's wrists undergo significant flexion, extension, ulnar deviation and radial deviation, positions that are highly correlated with injury. This method of propulsion also requires that the user's shoulders undergo significant internal rotation and abduction under a large amount of force, which is greatly correlated with shoulder injuries, especially those relating to the rotator cuff.
Currently, approximately 50% of long-term, independent wheelchair users experience an upper extremity injury due to the present propulsion system. The issues associated with overuse are becoming evident mainly in the forms of muscle pain, torn rotator cuffs, tendonitis, joint degeneration, and carpal tunnel syndrome. Furthermore, the standard propulsion system requires a large amount of strength to operate, and utilizes small muscle groups that are not suitable for supporting large amounts of repetitive force. The significant force required to propel this system forces weaker users and those with less dexterity of the hand. (Over 33% of wheelchair users experience difficulty in grasping activities with their fingers and more than 31% experience difficulty in holding a pen or a pencil.) to resort to the more expensive and burdensome electric wheelchairs, or to require attendant propulsion. However, MWCs have many advantages over their electric counterparts. For instance: the MWC can be easily transported, as most weigh less and can be folded and simply placed in vehicles for transportation; physically, the MWC provides upper body exercise and helps prevent muscular atrophy; psychologically, the MWC provides increased independence and self-reliance; furthermore, in terms of cost, the MWC is significantly more affordable than its current alternatives.